In the manufacture of wood, plastic or aluminum parts that have edges that are curved such as wood in furniture, plastic in signs and aluminum in aircraft, the curved parts must be cut with a band saw or router. A band saw requires a skilled operator to guide the blade to the line which outlines the desired shape of the part to be cut out. Because the final shape and size is controlled only by hand eye coordination, no two parts are identical. The other method is to use a router which uses a template to control its cutting path. Although it is still a hand operated machine of similar basic cost, the fact that a template is used to control the cutter path enables even an unskilled operator to produce large quantities of parts that are all identical in size and shape.
Routing machines normally consist of a high speed motor or belt driven spindle in the 20,000 RPM range which is coupled with a side milling tool having a number of ridges defined by flutes to provide clearance for removal of cut material.
These high speed motors or spindles with their side milling tool, are used in three basic types of routing machines; portable, broken arm (radial arm), and pin type routers. The portable and broken arm are similar in that they both use a guide bushing to guide against the template with the cutting tool extending down through the center of the bushing thus requiring an off-set template to allow for the bushing diameter which is larger than the cutting tool diameter. Thus special templates must be made up to accomodate the bushing to cutter relationship.
The pin type router uses a stationary pin that is in exact axial alignment with the cutting tool and is interchangeable to correspond to the diameter of the cutting tool, which allows the template to be the exact shape and size of the part being manufactured. In this case a sample chart can often be used as a template.
There are presently two basic types of pin routers on the market; the overhead router and my Inverted Router. The overhead router has been in existence for over 60 years. These machines have always been built basically the same since their inception. This normally consists of a high speed spindle, either direct motor driven or belt driven mounted to an overarm directly above the table with a guide pin mounted in the table in exact alignment with the spindle above. With the guide pin mounted in the table, the template must be lifted and placed over the guide pin obscuring the operator's view of the template configuration. The work piece is clamped to the template and all the operator can see is a blank piece of material and a very dangerous cutting tool in front of his face. The cutter is lowered into the work piece with a foot pedal control either mechanically or pneumatically. The piece part and template are clamped together as one unit, and are moved along the desired path which is dictated by the template. Keeping the guide pin engaged in the template groove is done by feel since the operator cannot see the pattern in the template as it is face down on the router table. With the operator's hands and the cutting tool engaged in the work piece at the same level, a slip of the hand could be hazardous if it contacted the cutting tool. The above has been the accepted method of routing in most all furniture and woodworking plants throughout the world over the last 60 years or more.
The other type of pin router is my Inverted Router. It also consists of a high speed spindle either direct motor driven or belt driven, mounted in the base of the machine with the spindle movable vertically to a point just below the top surface of the router table. The retractable guide pin is mounted in the over arm of the router. In other words, guide pins and router bits have traded places in the Inverted Router compared to the old style over head machine.
The many advantages to the inverted type router are; the template is on top of the work piece face up so the operator can engage the guide pin into the template visually; the shape in the template is visible so the path of the template is easily followed; the cutting tool comes up from below the table, controlled by a foot pedal (either mechanically or pneumatically) and engages the work piece which is below the template; the cutter is obscured by the template so the operator's hands are not exposed to the cutting tool. While the cutting tool is cutting its path through the work piece a very efficient suction system is helping along with gravity and the cutting action of the tool, to pull the chips out of the cut which improves cutting efficiency and makes for better working conditions for the operator. Noise levels are much improved on the Inverted Router since high speed spindle noise is confined to the base of the machine below the table rather than up on the over arm near the operator's ears. Simple templates are another main advantage of my Inverted Router. With the template on top and the piece part sandwiched between the table and template, firm clamping of part and template is not necessary. Light finishing nails, shallow spurs or even double faced tape can be used to keep the template or sample part from slipping while cutting a new part. The above feature brought to realization that the Inverted Router was ideal for the small low production shop as well as the large high volume plant.
The model 2003 Inverted Router wad developed for this small shop market.
A unique slide was needed for this machine to enable the operator to have full plunge and depth control on this inexpensive but accurate machine.